Dry-season irrigation alters carbon dynamics in tropical forest regrowth
Daniel
Jacob
Zarin, University of Florida, zarin@ufl.edu
(Presenting)
Débora
Veiga
Aragão, Universidade Federal Rural da Amazonia, debora@ufra.edu.br
Maristela
Machado
Araújo, Universidade Federal Rural da Amazonia, maristela@ufra.edu.br
Cláudio José
Reis de Carvalho, EMBRAPA, carvalho.bel@terra.com.br
Lucas
Fortini, University of Florida, lfortini@ufl.edu
Izildinha
Miranda, Universidade Federal Rural da Amazonia, izildinhamiranda@uol.com.br
Stephen
S.
Mulkey, University of Florida, smulkey@ufl.edu
Francisco
Assis
Oliveira, Universidade Federal Rural da Amazonia, fassis@ufra.edu.br
Patricia
Delamonica
Sampaio, University of Florida, psampaio@ufl.edu
Joanna
Tucker, University of Florida, jmtucker@ufl.edu
Steel
Silva
Vasconcelos, University of Florida, svascon@ufl.edu
For three consecutive dry seasons (2001-2003) we have irrigated four 20 x 20 m plots in 2 ha of forest regrowth near Castanhal, Pará, Brazil. The stand was last abandoned in 1987 following multiple cycles of shifting cultivation dating back to the 1940s. The experiment was designed to examine the role of moisture as a constraint on carbon dynamics in tropical forest regrowth. Irrigation is applied in the late afternoon at a rate of 5 mm day-1, corresponding to regional estimates of daily evapotranspiration. Relative to measurements made in a corresponding set of control plots within the same stand, dry-season irrigation has significantly altered carbon dynamics by increasing leaf-level assimilation, litter decomposition, and soil respiration during the dry-season. Irrigation also appears to accelerate seed germination, as well as the onset of reproduction in some plants. Treatment effects have occurred in the context of dynamic successional processes, which thus far do not bear an obvious treatment impact. Since our first pre-treatment stand inventory in 1999, dominant pioneer species (Lacistema pubescens, Vismia guianensis) have suffered 30 percent mortality, and stand-level stem density has declined 20 percent, while basal area and average stem height have increased by 15 and 10 percent, respectively.
Submetido por Daniel Jacob Zarin em 17-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)